"The demand for secure, cloud\u2011native applications is soaring, and companies are racing to build robust token\u2011gateway platforms. As a Senior Full\u2011Stack Engineer at Best\u202fBuy, you\u2019ll shape the control\u2011plane UI while steering backend services, making a direct impact on product security. This role blends deep React expertise with Java/Spring mastery, offering a chance to mentor and influence architectural decisions.\n\n# Job Summary\nWe are seeking a product\u2011minded Senior Full\u2011Stack Engineer to design and implement scalable React user interfaces and robust Java/Spring REST APIs for an enterprise token and gateway service. The role involves daily collaborative design sessions, architectural decision\u2011making, and mentoring junior engineers while championing test automation and coding standards.\n\n# Top 3 Critical Skills Table\n| Skill | Why it's critical | Mastery Level |\n|-------|-------------------|--------------|\n| React JS | Powers the control\u2011plane UI that customers interact with daily | Senior |\n| Java/Spring | Provides the secure, high\u2011performance backend services and APIs | Senior |\n| OAuth / Security Flows | Guarantees that token handling meets enterprise security requirements | Senior |\n\n# Interview Preparation\n1. **How would you design a React component that consumes a paginated OAuth\u2011protected REST API?**\n - *What the interviewer is looking for:* Understanding of token handling, pagination logic, error handling, and performance optimization in React.\n2. **Explain the differences between Spring MVC and Spring WebFlux for building REST services. When would you choose one over the other?**\n - *What the interviewer is looking for:* Knowledge of reactive vs. imperative programming models and trade\u2011offs related to scalability and latency.\n3. **Describe a strategy to migrate a legacy Java service to a Spring Boot microservice while preserving existing OAuth security flows.**\n - *What the interviewer is looking for:* Experience with incremental refactoring, backward compatibility, and security integration.\n4. **What are the key benefits of using Playwright for end\u2011to\u2011end testing in a React application, and how would you integrate it into a CI/CD pipeline?**\n - *What the interviewer is looking for:* Familiarity with modern testing tools, CI/CD concepts, and maintaining test reliability.\n5. **Walk us through a pair\u2011programming session you led. How did you ensure knowledge transfer and code quality?**\n - *What the interviewer is looking for:* Collaboration skills, mentorship approach, and commitment to coding standards.\n\n# Resume Optimization\n- React JS (5+ years)\n- Java (4+ years)\n- Spring Framework\n- REST API Development\n- OAuth / Security Flows\n- CI/CD Pipelines\n- Playwright\n- Vite\n- Product\u2011Engineer Mindset\n- Pair Programming / XP\n\n# Application Strategy\nWhen reaching out to the recruiter, send a concise email that greets the hiring manager, attaches your resume, and clearly highlights your top relevant skills. Make sure to mention related skills you possess, such as **React, Java/Spring, and OAuth security**, and reference specific projects where you built scalable UIs or secure APIs. Emphasize your experience mentoring engineers and driving test\u2011automation initiatives.\n\n# Career Roadmap\n| Current Role | Typical Experience | Core Focus | Next Position |\n|--------------|--------------------|------------|---------------|\n| Senior Full\u2011Stack Engineer | 8+ years, full\u2011stack ownership | Architecture, mentorship, security | Lead Full\u2011Stack Engineer |\n| Lead Full\u2011Stack Engineer | 10\u201112 years, cross\u2011team leadership | Strategy, large\u2011scale systems, hiring | Engineering Manager |\n| Engineering Manager | 12\u201115 years, people & project management | Delivery excellence, org design | Director of Engineering |\n| Director of Engineering | 15+ years, multi\u2011team oversight | Vision, budgeting, product alignment | VP of Engineering |\n"